1. Field of the Invention
The present invention relates to guidance and control systems for vehicles in flight, and more particularly to a method and apparatus for tracking the center of gravity of an air vehicle for tracking changes in the position of the Center of Gravity (COG) due to fuel consumption or changes in payload of a vehicle in flight.
2. Description of the Related Art
Knowledge of the position of the center of gravity of an airborne vehicle is very important for accurate determination of the vehicle attitude. Knowledge of the position of the center of gravity is also essential for proper calculation of the various aerodynamic forces and torques on an aircraft or missile body, for selection of the proper control strategy, and for ensuring vehicle stability and effective guidance. However, due to the difficulty in tracking center of gravity movement during flight, many of proposed methods for attitude determination of aircraft or guidance of vehicles are normally simplified by making certain assumptions, such as that the mass of the vehicle is constant during the planned mission, or that the instruments are always located at the center of gravity (COG).
However, the migration of the COG with respect to the vehicle's fixed axis during flight could lead to serious difficulties in stabilizing and maneuvering of the aircraft. For example, in the case of fighter airplanes, the change in mass comes not only from the release of the payload, but also from fuel consumption. In the case of a tactical missile, the rapid consumption of the fuel could lead to major changes in the mass and the location of the COG of the missile.
There is a need for a method and system for determining the center of gravity of a vehicle in flight that will continuously recalculate the center of gravity in order to adjust for changes in the position of the center of gravity under the dynamic conditions of flight. Thus, a method and apparatus for tracking the center of gravity of an air vehicle solving the aforementioned problems is desired.